Twenty-four chapters reconstruction

About reconstruction

Reconstruction of the definition:

1. Without changing the external behavior of the software provided, it changes its internal structure, to make it easier to understand to be modified;
2. The possible a program into multiple components.

Reasons for reconstruction

• Code duplication;
• Lengthy routine;
• Too long or too deep nested loop;
• Class interface failed to provide a consistent level of abstraction;
• It has too many parameters list of parameters;
• Review inner class is often limited to a part;
• Changes lead to the same modifications to the plurality of classes;
• The same changes to the system of inheritance;
• caseStatements need to do the same modifications;
• At the same time the relevant data used did not like the way the organization;
• Class member functions using other features even more features than the use of their own class;
• Excessive use of the basic data types;
• A class doing nothing;
• Transmitting a series of data subroutine stray;
• Middleman objects have nothing to do;
• A relationship similar to other classes too close;
• Subroutine named improper;
• Data member is set to be common;
• A derived class uses only a small part of the base class member function;
• Note codes are used to explain difficult;
• The use of global variables;
• Before using the setup code subroutine call or after the call using the finishing codes;
• The program seems to be some code that will be used at some point in the future.

Specific reconstruction

Data-level reconstruction

• Constant alternative name appliances mysterious value;
• The variable names more clearly and deliver more information;
• Indicating inlined;
• Instead a function expression;
• Introducing the intermediate variable;
• Instead of a plurality of single-use multipurpose variables variables;
• Local variables used in the topical use instead of the parameter;
• The basic data types into a class;
• The group type code into a class or enumerated type;
• Converting a group type code is a base class and derived classes corresponding;
• Converting the number of group objects;
• The encapsulated cluster;
• Class data to replace conventional recording.

Statement-level reconstruction

• Decomposition of Boolean expressions;
• Complex Boolean expressions to convert into a table named accurate Boolean function;
• Duplicated code fragments of different conditional statements combined portion;
• Use breakor returnnot the loop control variable;
• In nested if-then-elsestatements Once you know the answer to return immediately, rather than assign a return value;
• Polymorphism replaced with conditional statements;
• Creating and using nullobjects instead of to detect a null value.

Subroutine-level reconstruction

• Or a method of extraction subroutine;
• The inside of the subroutine biphenyl;
• Converting subroutine lengthy class;
• Alternatively simple algorithm complexity algorithm;
• Increase parameter;
• Delete parameters;
• The query operations independent from the modify operation;
• Merging similar subroutine, distinguishing their function parameter;
• The behavior depends on the parameters of the subroutine split open;
• Pass an entire object rather than a particular member;
• Pass specific member instead of the entire object;
• The packaging operations downcast.

Class implements operations

• The value of the reference object into the object;
• Virtual function instead of the initialization data;
• Changing the position of the member function or a data member;
• The code extraction number Laid derived class;
• The code is similar to the combination is placed in the base class.

Reconstruction of class interface

• The member functions of the class into another;
• A class into two;
• Delete class;
• Remove trust relationships;
• Remove the middleman;
• With the commission instead of inheritance;
• The introduction of an external member function;
• Extended by the introduction;
• Member variable of encapsulating exposed;
• For class member can not be modified, deleted the relevant Set()member function;
• Hide those member functions can not be used outside the class;
• Package does not use the member function;
• Very similar to those achieved merging the base and derived classes.

System-level reconstruction

• Create a clear index of the source data can not be controlled;
• The class one-way links instead of class two-way link; the two-way link to group class one-way links;
• Factory Method pattern rather than a simple constructor;
• Substituted with exception error handling code, converting or do the opposite direction.

Security reconstruction

• Save initial code;
• Please smaller pace of reconstruction;
• The list of things to do to a bar;
• Set a parking lot;
• More use of the checkpoint;
• The use of compiler warnings;
• retest;
• Increase test cases;
• Check the modification of the code;
• According to reconstruct reconstruction method to adjust the level of risk;

The case should not be reconstructed

• Do not change synonymous after reconstruction as almost;
• Instead of using reconstituted avoid overwriting.

Reconstruction strategy

• Reconstructed in increasing routine;
• Add to reconstruct the class time;
• Reconstruct the defect at the time of repair;
• Watch easy-to-module error;
• Focus on highly complex modules;
• Your hands are working to improve the code in the preservation of the environment;
• Clean, clearly defined boundaries between the code and the code is bad, then try to move the code through this border.

Points

• Modify the things you have to face a lifetime of the program ,, including not only the initial development stage, including after the initial release;
• In either modify the software quality in the well, or worse. The first law of software evolution is the evolution of the code should enhance the intrinsic quality of the program;
• The key to success lies in the reconstruction of many programmers should learn the warning code requires attention to those marking the reconstruction;
• Another element of the success of the reconstruction is the programmer should master a large number of specific reconstruction method;
• The last point is that the success of the reconstruction of reconstruction have security policies;
• Reconstruction of the development phase is the best time to enhance the quality of the program, because you can make change instantly just produce dreams into reality.